JPH07258272A - Preparation of methylchlorosilane - Google Patents

Abstract

PURPOSE: To obtain methylchlorosilane with good efficiency, high selectivity and high yield by reacting methyl chloride with silicon in the presence of a mixed catalyst comprising copper oxide, etc.

CONSTITUTION: In the presence of a mixed catalyst comprising preferably 0.5-10 (wt.)% (based on the silicon used) copper oxide, preferably 0.5-60% (based on the copper oxide) zinc oxide and preferably 200-8,000 ppm (based on the copper oxide) metallic antimony, methyl chloride is reacted with silicon to obtain the desired methylchlorosilane.

COPYRIGHT: (C)1995,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to a process for preparing methylchlorosilane by reacting methyl chloride with silicon in the presence of a mixed catalyst consisting of copper oxide, zinc oxide and metallic antimony.

[0002]

BACKGROUND OF THE INVENTION The preparation of methylchlorosilanes (direct synthesis) by reacting silicon with methyl chloride in the presence of suitable catalysts or mixed catalysts is already known. For example, in U.S. Pat. No. 33,452, copper,
Direct mixing using a mixed catalyst consisting of zinc and tin elements or compounds is described. The quantity ratio of catalyst, copper, zinc and tin to each other in this way has a strong influence on this method, especially on the productivity and the selectivity, but in the form in which the catalyst is loaded in the contact material, for example metal Whether it is an alloy or a compound is of secondary importance. Moreover, the production rates achieved with tin as catalyst are relatively low.

D. I. Rainer et al., Chemical Abstracts Vol. 57, 6
669g (1962) describes a direct synthesis method using a silicon-copper alloy as a catalyst with zinc and antimony. If the copper has not yet been alloyed during silicon production, the production of silicon-copper alloys is energy intensive and requires additional equipment. Control of silane synthesis is more difficult because the silicon to copper ratio was previously determined by this alloy. Changes in the Si: Cu ratio in the contact material during the reaction cannot be compensated correspondingly quickly. When metallic copper is used, the silane production rate (silicon weight and silane per hour unit) achieved is lower than that of copper oxide. However, silicon-copper oxide alloys cannot be produced on the basis of electrochemical voltage series and are unstable.

In addition to copper-silicon alloys, copper is often used in the form of metallic copper, copper chloride, copper formate or copper oxalate. The production of these copper compounds in relatively pure form and in suitable particle size is energy intensive and costly. Recycling to recover spent copper into the starting compound is relatively expensive. Copper formate and copper oxalate are heat labile, that is, they decompose spontaneously upon heat load. When copper chloride is used, the decomposition of methyl chloride produces concentrated tar and soot on the contact material, which reduces reactivity.
Copper metal has the disadvantage that it is ductile and therefore difficult to machine into a powder having a suitable particle size and surface. Another disadvantage of metallic copper catalysts is their low selectivity with respect to dimethyldichlorosilane. For example, the use of copper oxalate with the elements zinc and antimony in a direct synthesis is described in German Patent (DD-A) No. 2935.
No. 06 specification.

Lieske et al., "First"
0th International Symposium on Organic Silicon Chemistry (Xth Inte
rn. Symposium on Organosi
licon Chemistry, 1993, Poz
nan, Polen, Abstract, p. 209) ”,
A direct synthetic method using a combination of copper oxide and zinc and antimony as a catalyst is described. Zinc metal spontaneously causes an exothermic redox reaction with a copper compound added during preparation of the contact material, for example, copper oxide, thereby impairing the safety of the process. During the reaction of the contact material with methyl chloride, metallic zinc is oxidized to ZnCl ₂ . Zn
Cl ₂ is partially volatile at the temperatures at which methylchlorosilane synthesis occurs. Therefore, ZnCl ₂ is expelled from the contact material during the reaction and either deposits in the cold equipment section or is carried out with the silane stream. Similarly, metallic zinc or Z
A significant increase in these components in the contact material occurs when nCl ₂ is used during the reaction with methyl chloride. However, in order to maintain the productivity of this process, a corresponding post-addition of these components is necessary, at the same time in the silane,
The unwanted content of zinc compounds in the equipment part and in the reaction dust will increase.

US Pat. No. 4,645,851 and US Pat. No. 4,616,613 describe mixed catalysts of copper oxide, zinc oxide, metallic antimony and other alkali metals or alkalis. Direct synthesis methods have been proposed in the presence of additives of earth metals or metal compounds, such as cesium chloride, calcium chloride or barium carbonate, but using only catalysts consisting of copper oxide, zinc oxide, metallic zinc and additives. It was just carried out. The disadvantage of such additives is that they often have to be used in relatively high concentrations in order to bring about the corresponding action, many additives are relatively expensive and are not suitable after the reaction. Need to be collected and deposited. For example, a high content of cesium chloride is needed to achieve high dimethyldichlorosilane selectivity and to increase productivity.

[0007]

The object of the present invention was to provide a method for producing methylchlorosilane by reacting methyl chloride with silicon, in which case other additions are made. Higher reaction rates and higher dimethyldichlorosilane selectivities can be achieved without the problems of physical problems such as increased process costs or treatment or recycling of additives after the end of the reaction.

[0008]

The object of the present invention is a process for the production of methylchlorosilane by reacting methyl chloride with silicon in the presence of a mixed catalyst consisting of copper oxide, zinc oxide and metallic antimony.

With the process according to the invention, it is possible to achieve a relatively high silane production rate without the need for additionally adding other elements or compounds, while at the same time achieving a relatively high dimethyldichlorosilane selectivity. . Another advantage of the present invention is that a reaction mixture consisting of silicon and a catalyst, referred to as a contact material, can be safely handled even at relatively high temperatures and the catalyst remains in the contact material in sufficient concentration during the reaction. That is.

The invention is based on the knowledge that the individual components used in the silicon / copper / zinc / antimony system also have a great influence on the process. Thus, for example, ZnO achieves higher production rates than Zn and ZnCl ₂ and avoids significant precipitation of zinc from the contact material.

The process is preferably carried out in a fluidized bed reactor, preferably at temperatures of 250 to 400 ° C., especially 250 to 360 ° C. Because it costs very little,
This method is most often used at ambient atmospheric pressure (about 0.1MP
a) -0.5 MPa, but higher pressures can also be used.

The process can be carried out with pure methyl chloride or a methyl chloride / inert gas mixture, for example nitrogen or argon can be used as the inert gas. The amount of gas flow is in an advantageous manner
Select to produce a fluidized bed in the reactor.

This method may be carried out continuously or discontinuously. By continuous is meant the continuous post-addition of the amount of reacted silicon and the amount of catalyst discharged with the reaction dust.

Methyl chloride or methyl chloride / inert gas-
In a preferred embodiment of the process according to the invention, the mixture is continuously introduced into the contact material, whereby a fluidized bed is produced. Unreacted methyl chloride and optionally inert gas and the gaseous methylchlorosilane formed are removed from the reactor. One or several cyclones separate the comminuted particles together from the gas stream if desired,
In doing so, a large quantity of particles which have been ground together from the contact material are returned to the reactor. The silane is subsequently separated from the residual dust and unreacted methyl chloride and fed to the distillation. The purified, unreacted methyl chloride can be fed back into the reactor.

From the particles which have been ground together and separated, the copper which is optionally contained, as well as from the reaction residue after the reaction has been completed, is recovered in a simple manner by the method described in US Pat. No. 5,306,328. It can be returned to the copper oxide used.

In a preferred embodiment of the process according to the invention, silicon with a particle size of less than 700 μm and more than 20 μm, particularly preferably less than 250 μm and more than 70 μm, is used. The average particle size of the silicon particles is preferably in the range from 100 to 200 μm, particularly preferably 130 to 1
It is in the range of 70 μm. The silicon used is generally> 99
It has a purity of%.

In the process according to the invention, copper is used in the form of a copper oxide-mixture or in the form of copper (II) oxide. General formula CuO
_In the case of mixed oxides of x, x has a value of 0.6 to 1, values of at least 0.7 being preferred. The copper oxide used can contain minor impurities such as iron, lead, zinc, aluminum, titanium, alkali- or alkaline earth metals or tin. The total amount of impurities must not exceed 3% by weight, the total concentration of lead being at most 0.005% by weight, and the total concentration of alkali metals and alkaline earth metals being at most 0.04% each. % By weight, the total concentration of barium and strontium being at most 0.008% by weight and the total concentration of tin being at most 0.2% by weight. Copper oxide is preferably used in a particle size of less than 25 μm, the average particle size being in the range 10 to 0.1 μm, preferably 7-1 μm, particularly preferably 5 to 1 μm.
The range is m. The copper oxide described is, for example, US Pat. No. 53.
No. 06328, the degree of oxidation can be adjusted to the expected value by the drying temperature and the residence time at this temperature.

Advantageously, 0.5 to 1 relative to the silicon used
0% by weight, particularly preferably 0.7 to 7% by weight, of copper oxide is used, 1 to 5% by weight being particularly preferred.

Zinc oxide is preferably used in the process according to the invention in a particle size of less than 25 μm, the mean particle size being in the range 15 to 0.1 μm, preferably 10 to 0.5 μm.
The range is m. The zinc oxide used is preferably 0.0
It has a lead content of less than 05% by weight and a tin content of less than 0.002% by weight. The total content of alkali metals and alkaline earth metals is at most 0.04% by weight, and the total content of barium and strontium is at most 0.008% by weight. Zinc oxide is, for example, Fluka Feinchemikali.
En GmbH, Germany). The amount of zinc oxide used is preferably 0.5 to 6 relative to copper oxide.
0% by weight, particularly preferably 2-40% by weight, ZnO, particularly preferably 5-30% by weight, are used.

In the process according to the invention, metal antimony is preferably used in a particle size smaller than 150 μm. In a preferred embodiment, antimony powder with a particle size of up to 45 μm is used. Antimony of this grain size is, for example, Alfa-Johnson.
Matthey GmbH, Germany). The amount of antimony used is preferably from 200 to 8000 ppm, in particular from 300 to 8,000, based on the copper oxide used.
4000 ppm, particularly preferably 500 to 2500
Use ppm antimony.

The preparation of the contact material is carried out by simply mixing the individual components at room temperature. The contact material can be subsequently heat-treated before charging into the reaction reactor, but is not carried out in an advantageous manner.

[0022]

EXAMPLES In the following examples, unless otherwise stated: a) amounts are by weight; b) pressure is 0.10 MPa (absolute); c) all temperatures are 20 ° C.

The results in the reaction of silicon with methylene chloride in the presence of a suitable catalyst depend on the composition of the contact material as well as the structure of the experimental equipment, the experimental implementation and the silicon used.
In order to eliminate these parameters and to clearly demonstrate the advantages of the present invention, various contact material compositions described in other literature were reacted with methyl chloride by standard methods in the experimental equipment described below. The results obtained at that time are described in Comparative Examples and Examples.

Silicon Used: Particle Size 70-250 μm Range Average Particle Diameter: 150 μm Commercially available under the name “Silgrain®” from Elchem, Norway.

Experimental apparatus: inner diameter 25 mm with heat coil
And a laboratory-fluid bed reactor consisting of a vertical glass tube with a height of 500 mm, a glass distribution frit, a distillation bridge with a brine-cooler and a receiver flask.

Standard Method: 120 g of silicon were intimately mixed with the catalyst to make the contact material and charged to the reactor. Heating the contact material to 340 ° C. under a stream of nitrogen of 40 l / h,
Traces of oxygen and moisture were removed from the reactor. Continuing,
40 l / h of methyl chloride were introduced into the reactor and the contact material was heated to 395 ° C. After an induction time in the range of 20-40 minutes, the formation of methylchlorosilane started, after which the reactor temperature was reduced to 360 ° C. The time from this point until 50 ml of methylchlorosilane was formed was referred to as a starting phase; subsequently, 30 ml of methylchlorosilane was collected,
At this time, this time was referred to as the manufacturing period.

The production rate of mg of methylchlorosilane / g of silicon × min was calculated by the following formula.

[0028]

[Outer 1]

The silane composition in the production period was analyzed by GC, and the contact material composition was analyzed by ICP at the end of the reaction.

The catalysts used, antimony and tin, have an average particle size of about 40 μm; zinc oxide, zinc and zinc chloride are used with an average particle size of 1-10 μm, and the copper catalyst has an average particle size of 2-4.
Used at μm. All catalysts are -200pp except tin.
It has less tin impurities than m. The content of alkali- and alkaline earth metals is <0.04% by weight for all catalysts, the total concentration of barium and strontium is <0.00
It was 8% by weight. Antimony, tin, zinc, zinc dioxide, zinc chloride, cesium chloride, antimony oxide and antimony chloride are commercially available from Alpha Johnson Massy, Germany, and copper oxide is US Pat. No. 5,306.
No. 328, the metallic copper was obtained by this method followed by drying under argon.

Comparative Example 1: US Patent (US-Re.) No. 3
Contact material composition according to 3452; it was found that higher production rates can be achieved under comparable conditions using antimony as catalyst (see Example 1).

Catalyst: Partially oxidized copper CuO _x x = 0.9; 6 g Zinc oxide 1 g Zinc 1000 ppm with respect to the copper oxide used Production rate in the starting period: 3.03 Production rate in the producing period: 2.87 reaction Subsequent contact material composition: Copper 0.85% Zinc 0.25% Tin 13ppm Silane composition during the production period: Me ₂ SiHCl: 0.4 wt% MeSiHCl ₂ : 0.8 wt% Me ₃ SiCl: 3.7 wt. % Me ₂ SiCl ₂ : 83.4% by weight MeSiCl ₃ : 7.2% by weight Comparative Example 2: Catalyst: Copper (II) oxide 6 g Zinc oxide 1 g Zinc 1150 ppm with respect to the copper oxide used Production rate: Starting period: 2 .41 production phase of the production rate: 2.21 the composition of the contact material after the reaction: 0.84% copper-zinc 0.19% tin 7ppm production life of the silane composition: Me ₂ SiHCl: 0.6 wt% MeS HCl _2: 1.3 wt% Me ₃ SiCl: 3.8 wt% Me ₂ SiCl _2: 81.7 wt% MeSiCl _3: 7.6 wt% Example 1: high production rates than antimony tin (Comparative Example 1) Demonstration of contact at room temperature Catalyst: Partially oxidized copper CuO _x x = 0.9; 6 g zinc oxide 1 g antimony, 1000 pp for copper oxide used
m Production rate in starting period: 3.03 Production rate in manufacturing period: 4.03 Composition of contact material after reaction: Copper 0.77% Zinc 0.20% Antimony 16ppm Silane composition in production period: Me ₂ SiHCl: 0 0.4 wt% MeSiHCl ₂ : 0.8 wt% Me ₃ SiCl: 4.4 wt% Me ₂ SiCl ₂ : 81.5 wt% MeSiCl ₃ : 8.0 wt% Example 2: Antimony is tin (Comparative Example 2). Demonstration of contacting at a better production rate Catalyst: Copper (II) oxide 6 g Zinc oxide 1 g Antimony 1000 ppm with respect to the copper oxide used Production rate in the starting period: 3.04 Production rate in the manufacturing period: 4.39 After reaction Contact material composition: Copper 1.46% Zinc 0.36% Antimony 14 ppm Silane composition during the manufacturing period: Me ₂ SiHCl: 0.2 wt% MeSiHCl ₂ : 0.9 wt% Me ₃ SiCl: 3.6% by weight Me ₂ SiCl ₂ : 81.9% by weight MeSiCl ₃ : 7.5% by weight Comparative Example 3: The production rate achieved by using metallic zinc is small compared to zinc oxide, Demonstration that zinc is more effused from the contact material in this case (comparison with Example 1, reported by Lieske et al.) Catalyst: partially oxidized copper CuO _x x = 0.9; 6 g zinc 0.8 g antimony, 1000ppm relative to the copper oxide used Production rate in the starting period: 3.14 Production rate in the producing period: 3.39 Composition of contact material after reaction: Copper 1.08% Zinc 0.07% Antimony 22ppm Silane in the producing period composition: Me ₂ SiHCl: 0.3 wt% MeSiHCl _2: 0.7 wt% Me ₃ SiCl: 5.4 wt% Me ₂ SiCl _2: 80.2 wt% MeSiCl ₃ 8.7 wt% Comparative Example 4: production rate achieved in comparison with zinc oxide by the use of ZnCl ₂ becomes small, the demonstration (Example 1 because the zinc is unloaded more than the contact material in this case Comparison) Catalyst: Partially oxidized copper CuO _x x = 0.9; 6 g Zinc chloride 1.7 g Antimony, 1000 ppm with respect to the copper oxide used Starting yield: 0.96-the experiment was stopped after 4 hours However, the production period was not achieved after 4 hours.

Composition of contact material after reaction: Copper 1.74% Zinc 0.09% Antimony 34 ppm Comparative Example 5: In the case of antimony, there is no drawback of high CsCl addition, but there is a difference that CsCl is added to Si / C
By adding the uO _x / ZnO / Sn- contact material, (compared with the US Patent US-A No. 4,661,413 Pat) demonstration that high production rates than antimony contact material is not achieved.

Catalyst: partially oxidized copper CuO _x x = 9; 6 g zinc oxide 1 g tin, based on the copper oxide used 1300 ppm cesium chloride 0.85 g starting production rate: 3.2 manufacturing production rate: 3.99 Composition of contact material after reaction: Copper 2.00% Zinc 0.29% Tin 42ppm Silane composition in the production period: Me ₂ SiHCl: 0.1 wt% MeSiHCl ₂ : 1.6 wt% Me ₃ SiCl: 1.2% by weight Me ₂ SiCl ₂ : 87.8% by weight MeSiCl ₃ : 5.9% by weight Example 3: Catalyst: partially oxidized copper CuO _x x = 0.8; 6 g zinc oxide 1.5 g antimony, used 1500ppm to the produced copper oxide Production rate in starting period: 2.90 Production rate in manufacturing period: 4.23 Composition of contact material after reaction: Copper 1.15% Zinc 0.37% Antimony 34ppm Concrete-life of the silane composition: Me ₂ SiHCl: 0.4 wt% MeSiHCl _2: 0.8 wt% Me ₃ SiCl: 4.6 wt% Me ₂ SiCl _2: 80.4 wt% MeSiCl _3: 8.4 wt% Comparative Example 6: Demonstration that a corresponding production rate cannot be achieved without Zn-addition Catalyst: Partially oxidized copper CuO _x x = 0.9; 6 g antimony, 1000 ppm with respect to the copper oxide used Starting phase Production rate: 0.04-The experiment was stopped after 4 hours, but the production period was not reached after 4 hours.

Composition of contact material after termination of reaction: Copper 1.10% Antimony 32 ppm Comparative Examples 7 and 8: Demonstration that a higher production rate can be achieved when metal antimony is used than when an antimony compound is used Catalyst: Part Oxidized copper CuO _x x = 0.9; 6 g Zinc oxide 1 g Comparative example 7: antimony, 1400 ppm with respect to copper oxide
-Antimony-calculated as metal.

Comparative Example 8: 1400 ppm based on antimony (III) chloride and copper oxide, calculated as antimony metal.

Production rate in the starting period: Comparative Example 7: 2.64 Comparative Example 8: 1.57 In Comparative Example 8, the production period was not reached after a reaction time of 4 hours and the reaction was stopped after 4 hours.

Production rate in the manufacturing period in Comparative Example 7: 3.1
3 Composition of contact material after reaction: Comparative example 7 Comparative example 1.16% by weight 1.47% by weight Copper 0.21% by weight 0.24% by weight Zinc 18 ppm 45 ppm Antimony Silane composition in production stage Comparative example 7: Me ₂ SiHCl: 0.5 wt% MeSiHCl ₂ : 1.2 wt% Me ₃ SiCl: 3.2 wt% Me ₂ SiCl ₂ : 82.1 wt% MeSiCl ₃ : 7.1 wt% Comparative Example 9: using metallic copper In the case of using copper oxide, the production rate achieved is lower than that of using copper oxide, and the obtained dimethyldimethylsilane-demonstration that the selectivity is low Catalyst: Metallic copper 4.8 g Zinc oxide 1 g Antimony, used 1250ppm relative to copper Production rate in the starting period: 2.43 Production rate in the producing period: 2.00 Composition of contact material after reaction: Copper 2.93% Zinc 0.60% Tin 40pp m Silane composition in the manufacturing period: Me ₂ SiHCl: 1.1 wt% MeSiHCl ₂ : 3.3 wt% Me ₃ SiCl: 3.6 wt% Me ₂ SiCl ₂ : 75.6 wt% MeSiCl ₃ : 13.0 wt %

Front page continuation (72) Inventor Bernd Pashaly Federal Republic of Germany Burghausen Robert-Koch-Strasse 167 (72) Inventor Herbert Straussberger Germany Mailing Heidegasse 4 (72) Inventor Willie Streckel German Federation Republic Mailing Neuhauser Strasse 8

Claims (4)

[Claims] 1. A process for producing methylchlorosilane, which comprises reacting methyl chloride with silicon in the presence of a mixed catalyst consisting of copper oxide, zinc oxide and metallic antimony. 2. Method according to claim 1, characterized in that 0.5 to 10% by weight of copper oxide are used, based on the silicon used. 3. The method according to claim 1, wherein 0.5 to 60% by weight of zinc oxide is used with respect to copper oxide. 4. 200 to 8000 ppm based on copper oxide
4. The method as claimed in claim 1, wherein the antimony is used.